Rectifier device



Sept. 10,1935. 5. RUBEN 2,014,239

RECTIFIER DEVICE Filed April 22, 1952 F|G.1. ML

INVENTOR SAMUEL RUBEN ATTORNEY temperature changes.

Patented Sept. 10, 1935 UNITED PATNT OFFICE 8 Claims.

This invention relates to a rectifier device, and more particularly it relates to a mercury vapor rectifier having contact means for controlling a local circuit by the movement of the cathode with The object of the invention is the provision of a long-life mercury vapor rectifier in which no arcing or local discharges upon the surface occur, through the employment of automatic means for connecting and disconnecting a local circuit when the cathode reaches a predetermined temperature.

In the operation of mercury vapor rectifiers it is necessary to connect by external means the high potential circuit or the circuit supplying the alternating current to be rectified, after the cathode has reached the operating temperature necessary for electron emission. Unless this is done, arcing or localized discharges occur on the cathode surface, causing its rapid destruction. In the prior art this is accomplished by the use of a delay relay actuated by the filament or cathode heater supply circuit, which connects the plate circuit only when the cathode is at the operating temperature.

By the terms of my invention this connection is automatically made by employing the cathode temperature rise to directly operate a set of contacts. This is accomplished by utilizing the thermal expansion of the cathode to move a contact member so that it closes a gap in a connected local circuit, or increases the surface pressure between the contact members, the latter being employed when the conductivity of one or both of the contact m mbers varies with the surface pressure impressed therebetween. The cathode movement employed is preferably lineal expansion; but a bimetallic couple may be used.

Broadly, the device of my invention comprises a mercury vapor rectifier, such as that described in my co-pending application bearing Serial Number 582,714, and employing a directly or indirectly heated thermo-expansible cathode supporting or otherwise controlling the movement of a contact member, to open or close a gap in a local circuit or to vary the conductivity of one or both contact members in the circuit through a variation in their surface pressure. In constructing the device, a substantial closure of the anode may be made at the ends thereof, as by metal caps, through which the cathode extends in its portions uncoated with the high emission oxide. These closures are for the purpose of restricting the ionized mercury to the direct discharge path between the high emission cathode surface and the opposite walls of the anode.

While I have described a device employing a contact control operating by cathode temperature in a rectifier tube, the same type of circuit control may be used in other devices, such as mercury vapor control tubes which are similar to the 5 rectifier device, except that a grid or control element is interposed between the emission element and the anode. A requirement of this type of tube also is that the plate circuit discharge be applied after the cathode has reached an operat- 10 ing temperature.

Reference is made to the accompanying drawing of an embodiment of the invention, in which Fig.

1 represents a rectifier tube, with a portion cut away to disclose the elements, and Fig. 2 a sec- 15 tional view at 22.

Referring to Fig. 1, at l is a nickel cathode cylinder coated with a high electron emission oxide and mounted upon ceramic cylinder 2, encasing a tungsten wire heater 3. Copper cylinder 20 anode t, mounted on support H, has at its ends copper caps 5 and 6, to restrict the ionized mercury vapor to the cathode-anode path. At one end of cathode I, is mounted tungsten spring 8, attached to but insulated from the cathode. 2 Glass bead Q, is mounted upon tungsten spring I I, attached to but insulated from the cathode, and movable contact member IE, on spring l3 rests upon glass bead 9. Contact member I2, is separated by a gap from fixed contact member [4, 30 and both contacts are connected in a local circuit represented by leads |5-l5a. Mercury and magnesium silicide, the latter as a getter, are contained in metal container I6.

In Fig. 2 the corresponding elements are indicated by the same numerals as used in Fig. 1.

In operation, the local circuit which may be the plate voltage supply circuit, is connected when the cathode is at operating temperature, at which 40 the cathode has expanded sufficiently to force bead 9 against lower contact I2 in spring 13 and is in turn forced against stationary contact I4, thereby closing local circuit leads |5-l5a.

What I claim is:

1. A rectifier device comprising an envelope containing mercury vapor and having therewithin an indirectly heated electron emission element, an anode surrounding the emission element, with means for confining the ionized vapor discharge to the discharge path between the cathode emission surface and the anode walls and two contact members to be connected in an external electrical circuit, one of said members being movable by the lineal expansion and contraction of the 5 emission element with changes of temperature thereof.

'2. A mercury vapor rectifier devicehaving an indirectly heated electron emission element, means for heating the emission element, a cooperating anode surrounding the emission element, with means for confining the ionized vapor discharge to the discharge path between the cathode emission surface and the anode walls, and a pair of contact members to be connected in an external electrical circuit and thermostatically controlled by the lineal movement of the emission element.

3. A rectifier device containing in mercury vapor, a pair of contact members to be connected in an external circuit, an indirectly heated emission element and a cooperating anode surrounding the emission element, with means for confining the ionized vapor discharge to the discharge path between the cathode emission surface and the anode walls, one of the contact members being movable by the lineal movement of the emission element.

4. A mercury vapor-filled rectifier discharge device comprising an evacuated envelope containing an indirectly heated electron emission element, an anode surrounding the emission element and having its ends substantially closed and two contact members operable with the lineal expansion and contraction of the emission element to control another external circuit.

5. A rectifier device containing mercury vapor, an indirectly heated emission element and an anode surrounding the emission element, with means for confining the ionized vapor discharge to the discharge path between the cathode emis sion surface and the anode walls, and means'for making the device operable by the expansion of the emission element, said means comprising a plurality of contact members to be connected in an external circuit, one of said members being and the anode, the 'uncoated portion of the cathode extending through the anode outlets, and

1. two contacts adapted to be connected in an external circuit, one of said contacts being movable by the lineal expansion or contraction of the cathode but being insulated therefrom.

7. A mercury vapor rectifier containing an indirectly heated cathode having part of its surface coated with a high electron emitting oxide, a tubular anode through which said cathode extends, means at the anode terminals for confining ionized mercury vapor to the discharge path between the coated cathode surface and the anode, the uncoated portions of the cathode extending through the outlets of the anode, two contacts adapted to be connected in an external circuit, one of said contacts being movable by the lineal expansion or contraction of the cathode,

8. A'rectifier device comprising an envelope containing an ionizable metal vapor and having therewithin an electron emission element having a coated and an uncoated portion, an anode the uncoated portion of the emission element extending through the anode outlets, means for confining the ionized vapor discharge to the discharge path between the emission element and the anode, and two contact members, one of said members being movable by the movement of the emis= sion element.

SAMUEL RUBEN. 

